[PATCH AUTOSEL 5.15 02/41] btrfs: fix fallocate to use file_modified to update permissions consistently

[PATCH AUTOSEL 5.15 02/41] btrfs: fix fallocate to use file_modified to update permissions consistently

[Sasha Levin]

From: "Darrick J. Wong" <djwong@kernel.org>

[ Upstream commit 05fd9564e9faf0f23b4676385e27d9405cef6637 ]

Since the initial introduction of (posix) fallocate back at the turn of
the century, it has been possible to use this syscall to change the
user-visible contents of files.  This can happen by extending the file
size during a preallocation, or through any of the newer modes (punch,
zero range).  Because the call can be used to change file contents, we
should treat it like we do any other modification to a file -- update
the mtime, and drop set[ug]id privileges/capabilities.

The VFS function file_modified() does all this for us if pass it a
locked inode, so let's make fallocate drop permissions correctly.

Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/btrfs/file.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index a1762363f61f..dc1e4d1b7291 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -2878,8 +2878,9 @@ int btrfs_replace_file_extents(struct btrfs_inode *inode,
 	return ret;
 }
 
-static int btrfs_punch_hole(struct inode *inode, loff_t offset, loff_t len)
+static int btrfs_punch_hole(struct file *file, loff_t offset, loff_t len)
 {
+	struct inode *inode = file_inode(file);
 	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
 	struct btrfs_root *root = BTRFS_I(inode)->root;
 	struct extent_state *cached_state = NULL;
@@ -2911,6 +2912,10 @@ static int btrfs_punch_hole(struct inode *inode, loff_t offset, loff_t len)
 		goto out_only_mutex;
 	}
 
+	ret = file_modified(file);
+	if (ret)
+		goto out_only_mutex;
+
 	lockstart = round_up(offset, btrfs_inode_sectorsize(BTRFS_I(inode)));
 	lockend = round_down(offset + len,
 			     btrfs_inode_sectorsize(BTRFS_I(inode))) - 1;
@@ -3351,7 +3356,7 @@ static long btrfs_fallocate(struct file *file, int mode,
 		return -EOPNOTSUPP;
 
 	if (mode & FALLOC_FL_PUNCH_HOLE)
-		return btrfs_punch_hole(inode, offset, len);
+		return btrfs_punch_hole(file, offset, len);
 
 	/*
 	 * Only trigger disk allocation, don't trigger qgroup reserve
@@ -3373,6 +3378,10 @@ static long btrfs_fallocate(struct file *file, int mode,
 			goto out;
 	}
 
+	ret = file_modified(file);
+	if (ret)
+		goto out;
+
 	/*
 	 * TODO: Move these two operations after we have checked
 	 * accurate reserved space, or fallocate can still fail but
-- 
2.35.1

[PATCH AUTOSEL 5.15 03/41] btrfs: do not warn for free space inode in cow_file_range

[Sasha Levin]

From: Josef Bacik <josef@toxicpanda.com>

[ Upstream commit a7d16d9a07bbcb7dcd5214a1bea75c808830bc0d ]

This is a long time leftover from when I originally added the free space
inode, the point was to catch cases where we weren't honoring the NOCOW
flag.  However there exists a race with relocation, if we allocate our
free space inode in a block group that is about to be relocated, we
could trigger the COW path before the relocation has the opportunity to
find the extents and delete the free space cache.  In production where
we have auto-relocation enabled we're seeing this WARN_ON_ONCE() around
5k times in a 2 week period, so not super common but enough that it's at
the top of our metrics.

We're properly handling the error here, and with us phasing out v1 space
cache anyway just drop the WARN_ON_ONCE.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/btrfs/inode.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 58053b5f0ce1..f270729a325d 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -1075,7 +1075,6 @@ static noinline int cow_file_range(struct btrfs_inode *inode,
 	int ret = 0;
 
 	if (btrfs_is_free_space_inode(inode)) {
-		WARN_ON_ONCE(1);
 		ret = -EINVAL;
 		goto out_unlock;
 	}
-- 
2.35.1